In order to reduce road noise due to pneumatic tires, there have been conventionally proposed a variety of techniques including, for example, proper adjustment of the structure of the bead portions or sidewall portions thereof (see Patent Document 1, for example). However, there is a limit to reduce road noise with a tire alone, and it has been required to propose a new technique.
Patent Document 1: Japanese patent application Kokai publication No. 2001-97011